The alert Montgomery County Sheriff’s office north of Houston seized a $220,000 grant from the U.S. Department of Homeland Security last year to buy and operate a 49-pound, half-million dollar ShadowHawk unmanned aerial surveillance drone to provide real-time, overhead pictures for deputies heading into harm’s way.

But when the sheriff’s department asked the Federal Aviation Administration for emergency approval to fly the rotary drone during a potentially hazardous raid on a seven-acre compound with nearly 300 pit bulls, the regulatory agency rejected the request.

The reason, Montgomery County Chief Deputy Randy McDaniel told a House subcommittee Thursday, was because the FAA insisted “there had to exist a `loss of life or potential loss of life’ before they would approve it.”

“But it’s frustrating to know that (the FAA) made a decision without a clear understanding of the actual operational considerations,” McDaniel said. “The deputies and investigators entering that compound potentially faced a large number of pit bulls and the threat of imminent loss of life.”

None of the dozen deputies or investigators suffered injuries during the raid with a search warrant late Tuesday at Spindletop Pit Bull Refuge in Willis, Texas, McDaniel said. The Humane Society seized 298 dogs at a site described by former employee Brandon Louth as “a living hell” for dogs.

Yet the episode highlights the challenges facing law enforcement agencies that seek approval for surveillance missions by the growing number of drones nationwide.

The hiccup also bolsters claims by McDaniel and Rep. Michael McCaul, R-Austin, that the U.S. Department of Homeland Security — and not the FAA — should approve law enforcement missions because DHS is more familiar with day-to-day operational requirements and the risk that drones could be hijacked by terrorists.

The FAA has given at least 106 federal, state and local agencies nationwide permission to operate 207 drones – a number expected to increase rapidly as the FAA fully phases low-flying drones weighing less than 55 pounds into the U.S. aviation system by 2015.

“We have responsibility for safety whether it’s unmanned aircraft or piloted aircraft,” said an FAA spokesman who spoke on condition of anonymity under administration policy.

The FAA’s nine-page policy on unmanned drones authorizes emergency flight approval for operations that “directly support emergency and law enforcement-type operations.” A mission can only be approved if “there is a situation of such distress or urgency that the possibility of loss of life is great,” the policy says.

Emergency operations are usually only authorized for humanitarian relief and natural disasters rather than law enforcement operations, the FAA official said.

McCaul, the congressman from Austin whose district stretches into Houston’s northwest suburbs, said the predicament encountered by the Montgomery County Sheriff’s department reinforces his call for the FAA to be limited to evaluating aviation safety alone, leaving it to agencies within the Department of Homeland Security to give the go-ahead to law enforcement missions.

“While the FAA is responsible for ensuring these systems fly safely in U.S. airspace, no federal agency is taking the lead to deal with the full implications of using unmanned aerial systems.” said McCaul, chairman of oversight and investigations for the House Committee on Homeland Security.

None of the DHS officials invited to testify accepted McCaul’s invitation to discuss the department regulating drones. McCaul said he would ask the committee staff to look into issuing a binding subpoena to require a DHS official to appear before his committee in hopes of encouraging President Obama to issue an executive order elevating the DHS role.

The ShadowHawk drone, manufactured by Vanguard Defense Industries based in Conroe, Texas, can fly 400 feet off the ground at 50 miles per hour and stay aloft for up to three hours. The manufacturer said it can loiter at 700 feet “without being heard or seen,” providing enforcement entry teams advantages in “high risk warrant (arrests), hostage rescue (and) domestic violence.” Variants can be armed or carry tear gas.